So earlier in the week (about 4 days ago) I checked my levels in my 55gal cichlid tank. The Nitrites were in the 9.0-10.0ppm range and the Nitrates were around the 40ppm range... I then tested the Ammonia and it was between .25-.50ppm. I did a 50% water change, changed 1 of the 2 cartiges in...